Secondhand Lions is cornier than the cornfields spread out in front of the dilapidated rural Texas manse inhabited by Robert Duvall and Michael Caine, playing grumpy old brothers with mismatched accents. (Caine, in fact, has accent enough for three actors -- one English, another maybe Texan, another perhaps Australian.) There is no shortage of ham-fisted metaphors, no paucity of windy speeches, no lack of moments that tug at the heart like a newborn clumsily grabbing for its mother. It borrows every trick from the sentimentalist's handbook as though its writer and director, Tim McCanlies (Iron Giant and Dancer, Texas Pop. 81), were behind the camera checking off the index: cute dogs, yup; gawky teen, right; grouchy but lovable codgers, uh-hunh; fast-talking baddie, you betcha; a sharing of life lessons, good to go; swashbuckling flashbacks, natch; lost treasure, why not.

Secondhand Lions might be considered almost courageous for its willingness to venture into such mushy territory without hip-waders for protection; it strays deep into the syrup-filled marsh and never once yells out for rescue. With its cast of Oscar-winners and nominees, including moon-eyed Haley Joel Osment, it just dares you to hate it and would think you a misanthrope for doing so. Hey, kids -- it sure beats readin'.

The scenario, better handled in Diane Keaton's movingly oddball Unstrung Heroes years ago, is worn down to the soles: Walter (Osment), a quiet teenage nebbish, is forced to spend a 1960s summer with two great-uncles he's never met, never even heard of, after his no-account mom, Mae (Kyra Sedgwick), strikes out for court reporting school in Fort Worth. Mae insists she's determined to make a good life for the two, though all she's ever done is muck things up with a succession of lousy boyfriends and a litany of lies. But her intentions are never any good: More than time to herself, Mae also wants Walter to find the hidden millions Hub (Duvall) and Garth (Caine) are rumored to have somewhere on their property, money they made (or, perhaps, stole) during the 40 years they disappeared from Texas and traveled God knows where.

Of the two old men, Hub's the crankier -- a former adventurer, we're told, who frets about being on the short end of living and now considers himself useless. He does everything he can to prove himself wrong -- lifting 50-pound bags of feed, fighting four teen toughs in a barbecue joint -- but knows, soon enough, he's done for. So he spends his nights sleepwalking (and sleep-fencing) down by the lake and pining for the One True Love who's been dead for decades. It's a role Duvall could play while napping; it's appropriate that here, he often does.

Caine's Garth is the kinder brother, a bespectacled storyteller happy to have spent years cooling himself in Hub's larger-than-life shadow. He welcomes Walter and talks him out of running away, sensing potential in the "sissy boy" dumped on them by no-good Mae. (He also wants to keep Walter around just to irritate the ingratiating family members who drop by to troll for a good spot in the will in case the stories about all that money are true.) It's Garth who spins for Walter extravagant tales of two young brothers who left Texas before World War I, ended up joining the French Foreign Legion, fought in North Africa and, in Hub's case, romanced a princess and defeated a one-eyed sheik.

The Arabian Nights action sequences -- perhaps fairy tales told by Garth to amuse a kid, or maybe just flashbacks to actual adventures -- are so energizing and engaging you wish McCanlies had made that movie. (Lawrence of Abilene, perhaps?) Christian Kane, as the young Hub, is a fedora-sporting, ponytail-wearing buccaneer with a sword in one fist and a beautiful princess (Emmanuelle Vaugier) in the other. Set in grand desert vistas and among millions of gleaming golden coins, the scenes with Hub are so enormous they swallow up the predictable, hugs-all-round drama unfolding back on the dilapidated ranch.

The most problematic part of Secondhand Lions is Osment, who seems less an awkward boy figuring out how to become a man than a robot pretending to be human; his scenes feel like outtakes from A.I. Everything he does feels forced and faked, like a third-generation copy of some kid he saw on a street long, long ago. Just as bad is Nicky Katt as a child-abusing con man who appears to have been lifted from a James Cagney gangster picture -- though the quicker he talks, the faster he's offscreen.

McCanlies has handled this material better already; his Iron Giant, with a huge heart beating beneath the animated tin can, taught a timid, fatherless child how to become a man, without resorting to sentiment. Secondhand Lions almost feels like a rough draft, a first-timer's awkward attempt. It seems like such a rookie move to insert into the story line a worn-out circus lion, shipped to the brothers to hunt till they realize it's too old to even crawl out of its crate. It's all Duvall can do to keep from pointing to the lion, turning to the camera and saying to the audience, "This is supposed to be me -- get it?" (He does it, anyway, damn near.) Ah, but what the grown-up curmudgeon deplores the little kid will dig, right? Right.